Systems and methods for latency reduction using map staggering

ABSTRACT

A scheduling unit is provided for managing upstream message allocation in a communication network. The scheduling unit includes a processor configured to determine (i) a number of channels communicating in one direction stream of the communication network, and (ii) a MAP interval duration of the communication network. The scheduling unit further includes a media access control (MAC) domain configured to (i) calculate a staggered allocation start time for each separate channel of the number of channels, and (ii) assign a different allocation start time, within the MAP interval duration, to each separate channel.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/116,775, filed Aug. 29, 2018. U.S. patent application Ser. No.16/116,775 claims the benefit of and priority to U.S. Provisional PatentApplication Ser. No. 62/551,521, filed Aug. 29, 2017, and to U.S.Provisional Patent Application Ser. No. 62/618,414, filed Jan. 17, 2018.All of these applications are herein incorporated by reference in theirentireties.

FIELD

This disclosure relates in general to the field of communications and,more particularly, techniques for reducing latency in cellular backhaulcommunications.

BACKGROUND

Today's communication systems may include separate wireless and wirelineportions, each of which may be owned and controlled by the same ordifferent operators. Present cable network operators, such as MultipleSystem Operators (“MSOs”), use Data Over Cable Service InterfaceSpecification (“DOCSIS”) networks for backhauling Internet traffic, butseparate networks, including mobile networks, other DOCSIS networks,Wi-Fi networks, and radio networks have limited to no visibility intoparts of the other network types. Each network type, whether DOCSIS orLTE, etc., may have separate traffic scheduling algorithms, and mayexperience higher latency due to internetwork visibility andcommunication.

A communication network that implements DOCSIS must manage the upstreamcommunications. DOCSIS upstream scheduling is presently based on a“request-grant approach.” In the request-grant approach, a requestmessage is sent from a cable modem (CM) to a cable modem terminationsystem (CMTS). The CMTS prepares a DOCSIS media access control (MAC)management message (MMM), called the MAP, and inserts an entry into theMAP indicating a grant for the CM. The grant entry in the MAP messagecontains an upstream service identifier (SID) associated with a serviceflow assigned to the CM, a transmission time signaled as a mini-slotnumber, and the number of bytes to be transmitted. The CMTS transmitsthe MAP to the CM, so that the CM can make use of the grant to send itsupstream data to the CMTS.

In the upstream direction, a conventional DOCSIS communication networkmay, for example, include a Wi-Fi device (not shown), which communicatesMAP messages through a gateway (e.g., a modem, not shown) over awireless communication pathway (not shown), using an 802.11ac wirelesscommunication protocol to an upstream modem termination system (MTS, notshown).

In operation, a DOCSIS network may experience latency in the upstreamtraffic as a result of several conditions, including (i) queuing delays,which result from transfer control protocol (TCP) flows sending trafficfaster than the link rate of the network, and (ii) request-grant delays,which constitute the time needed to fulfill the request-grant approach,that is, the “request-grant time.” There are many factors that determinethe request-grant time in DOCSIS. The DOCSIS specification contains adetailed analysis of the request-grant delay 0. For DOCSIS, the minimumdelay is generally every second MAP time interval, plus some circuit andqueuing delay. In DOCSIS 3.0, the typical CMTS uses a 2 ms MAP timeinterval, but in some cases, the CMTS has been known to exhibit a 5 msminimum request-grant response time 0.

For upstream scheduling, the typical CMTS uses a scheduling algorithmthat may significantly impact the length of the request-grant delay. Forexample, if the CMTS is using a best effort (BE) scheduling algorithm,some requests made in a contention slot will fail on their firstattempt. One solution to this problem has been for the CMTS to use areal-time polling service (rtPS) scheduling algorithm, which places therequest in a dedicated slot to ensure successful requests. However, BEscheduling algorithms achieve better performance than rtPS schedulingalgorithms in the case where DOCSIS is idle, since the idle state willleave many request contention slots available. Accordingly, BEalgorithms provide lower latency than rtPS algorithms in idle states,but for busy systems, rtPS algorithms achieve lower net latency than BEalgorithms, due to the fact that the BE algorithm is required to repeatrequests often, whereas the rtPS is able to provide guaranteed latency.

In some communication systems, requests may also be sent as a piggybackmessage with a data packet. Such piggybacking techniques aredeterministic within a flow, and avoid contention. For lightly loadedsystems and frequency division duplexing (FDD) for long term evolution(LTE), DOCSIS 3.0 has a minimum request-grant delay of approximately 5ms, while 4G LTE has a minimum request-grant delay of about 18-24 mswithout re-transmission, and 26-34 ms with one hybrid automatic repeatrequest (HARM) retransmission. These latency values will increase underhigher loads or if time division duplexing (TDD) is used in LTE.

The DOCSIS request-grant loop delay has many contributing factors thatlead to having an upstream latency longer than required by manyapplications, such as require small cell backhaul, for example.Fundamental components of the request-grant delay in DOCSIS include (i)MAP generation time (100-200 μs), (ii) MAP-advance time (100 μs-20 ms),(iii) MAP interval (1 ms-6 ms or greater), and (iv) grant servicing timeallowed to the CM (650 μs). Where an upstream transmission constitutes asingle upstream channel, the request-grant delay is approximately equalto the sum of these four fundamental components, under loadedconditions, e.g., when the CMTS is forced to insert contention requestperiods. At present, in the case of multiple upstream channelconfigurations, approximately the same request-grant delay calculationapplies, because the MAP intervals are aligned (in time) across theactive upstream channels, as illustrated below with respect to FIG. 1 .

FIG. 1 is a timing diagram illustrating a conventional distribution 100of MAP messages 102 for four upstream channels 104 in a communicationsystem (not separately shown) implementing DOCSIS. In this example,distribution 100 includes a MAP interval 106 of 2 ms. In typicaloperation of a conventional DOCSIS communication system, the CMTSscheduler operates over a 2 ms MAP interval (i.e., MAP interval 106),and gives each service flow of channels 104 only one grant for each MAPinterval 106. Accordingly, this operation results in the nominal 2 msinterval between grants for messages 102 on each upstream channel 104.In the example illustrated in FIG. 1 , each downward arrow represents aparticular MAP message 102 being sent from the CMTS for a particularchannel 104.

In conventional multi-channel DOCSIS networks, transmission ofindividual MAP messages 102 from a particular channel 104 are aligned intime to coincide with the transmission of MAP messages 102 from otherchannels 104, as illustrated in FIG. 1 . That is, conventional DOCSISnetworks align the MAP intervals across bonded upstream channels 104,such that the allocation start time of a particular MAP interval 106 isapproximately the same (i.e., within a few μs) for all four channels104. As illustrated below with respect to FIG. 2 , this conventionalinterval alignment results in unnecessarily latency in the case ofsimultaneous grant requests from different channels 104.

FIG. 2 is a sequence diagram illustrating a conventional transmissionopportunity grant effect 200 according to conventional distribution 100,FIG. 1 . Effect 200 is illustrated with respect to MAP interval 106,FIG. 1 , which includes a first component 202, a second component 204,and a third component 206. In this example, first component 202represents the next MAP fulfillable time (e.g., 0.6 ms), secondcomponent 204 represents the MAP generation time (e.g., 0.2 ms), andthird component 206 represents the MAP time for advance and contentionrequest region (e.g., 1.2 ms).

In operation of effect 200, the alignment of allocation times for allchannels 104 creates a global allocation start time 208 within a domain210 of the MAC layer (not shown in FIG. 2 ) for each upstream (US)transmission 212 to wait for the single MAP interval 106. Moreparticularly, because MAC domain 210 of conventional transmissionopportunity grant effect 200 applies global allocation start time 208for all upstream transmissions 212, a window 214 in which requests maybe fulfilled in the next MAP interval 106′ (i.e., for the lowest latencyopportunity) is only a fraction of MAP interval 106 (approximately thefirst 25% of MAP interval 106, approximately corresponding to just shortof the completion of first component 202, i.e., less than the first 0.6ms of the 2 ms MAP interval 106). In the case of piggybacking, window214 indicates the amount of time to make the piggyback request justbefore cutoff.

In this conventional scheme, a minimum value 216 for the request-grantloop delay is the sum of the MAP generation time (i.e., second component204, e.g., 0.2 ms) plus the MAP advance time (i.e., third component 206,e.g., 1.2 ms), or 1.4 ms in this example. Under this scheme, a maximumvalue 218 for the request-grant loop delay therefore effectively becomesthe sum of minimum value 216 (e.g., 1.4 ms), plus the length of 1 MAPinterval (e.g., 2 ms), or 3.4 ms in this example. Maximum value 218 isillustrated in FIG. 2 with respect to EXAMPLE 1, which demonstrates agranted transmission opportunity (TxOP) 220(1) only after expiration oftwo full MAP intervals 106, e.g., at 4 ms. Similarly, minimum value 216is illustrated in FIG. 2 with respect to EXAMPLE 2, which demonstrates agranted TxOP 220(2) only after expiration of the first MAP interval 106,e.g., at 2 ms.

SUMMARY OF THE INVENTION

In an embodiment, a scheduling unit is provided for managing upstreammessage allocation in a communication network. The scheduling unitincludes a processor configured to determine (i) a number of channelscommunicating in one direction stream of the communication network, and(ii) a MAP interval duration of the communication network. Thescheduling unit further includes a media access control (MAC) domainconfigured to (i) calculate a staggered allocation start time for eachseparate channel of the number of channels, and (ii) assign a differentallocation start time, within the MAP interval duration, to eachseparate channel.

In an embodiment, a method of scheduling upstream data traffic over acommunication network is provided. The method includes steps ofdetermining a MAP interval duration according to a communicationprotocol of the communication network, counting a number of upstreamtransmission channels in the communication network, dividing the MAPinterval duration by the number of upstream transmission channels,calculating an allocation start time interval based on the step ofdividing, and assigning each of the number of upstream transmissionchannels a different allocation start time within the MAP intervalduration.

BRIEF DESCRIPTION

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a timing diagram illustrating a conventional distribution ofMAP messages for four upstream channels in a communication systemimplementing DOCSIS.

FIG. 2 is a sequence diagram illustrating a conventional transmissionopportunity grant effect according to the conventional distribution ofMAP messages depicted in FIG. 1 .

FIG. 3 is a timing diagram illustrating an exemplary staggereddistribution of MAP messages for four upstream channels in acommunication system implementing DOC SIS, in accordance with anembodiment.

FIG. 4 is a sequence diagram illustrating an exemplary transmissionopportunity grant effect according to the staggered distribution of MAPmessages depicted in FIG. 3 .

FIG. 5 is a timing diagram illustrating an exemplary staggereddistribution of MAP messages for sixteen upstream channels in acommunication system implementing DOC SIS, in accordance with anembodiment.

Unless otherwise indicated, the drawings provided herein are meant toillustrate features of embodiments of this disclosure. These featuresare believed to be applicable in a wide variety of systems including oneor more embodiments of this disclosure. As such, the drawings are notmeant to include all conventional features known by those of ordinaryskill in the art to be required for the practice of the embodimentsdisclosed herein.

DETAILED DESCRIPTION

In the following specification and the claims, reference will be made toa number of terms, which shall be defined to have the followingmeanings.

The singular forms “a,” “an,” and “the” include plural references unlessthe context clearly dictates otherwise.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about,” “approximately,” and “substantially,” are notto be limited to the precise value specified. In at least someinstances, the approximating language may correspond to the precision ofan instrument for measuring the value. Here and throughout thespecification and claims, range limitations may be combined and/orinterchanged; such ranges are identified and include all the sub-rangescontained therein unless context or language indicates otherwise.

The systems and methods described below provide latency reductiontechniques that are advantageous for communication systems implementingDOCSIS, and also for other communication systems that schedule MAPmessages. The present embodiments are described with respect to upstreamMAP scheduling, but may also be implemented in some downstreamscheduling circumstances. The present MAP staggering techniques improveover conventional MAP alignment schemes by significantly reducing themaximum request-grant loop latency between upstream channeltransmissions.

In an exemplary embodiment, an upstream scheduling unit staggers MAPinterval allocation start times for different upstream channelsaccording to a duration of the MAP interval, divided by the number ofupstream channels at issue, such that the “effective map interval” maybe reduced, but without sacrificing the beneficial attributes (e.g.,lower overhead, less segmentation, other efficiency improvements, etc.)of the existing, longer MAP interval. That is, the present latencyreduction techniques are particularly effective in the case wheremultiple upstream channels are in use. By staggering the start time ofthe MAP interval for each upstream channel in use, the request-grantloop delay for upstream transmissions is effectively, and significantly,reduced in the aggregate of multiple channels.

FIG. 3 is a timing diagram illustrating an exemplary staggereddistribution 300 of MAP messages 302 for four upstream channels 304 in acommunication system (not separately shown) implementing DOCSIS, andusing a standard-duration MAP interval 306 (e.g., 2 ms). Staggereddistribution 300 is similar to conventional distribution 100, FIG. 1 ,with respect to the respective individual components thereof (i.e., MAPmessages, channels, MAP interval), but significantly differs from theconventional approach with respect to the staggered allocation of MAPmessages 302. More particularly, in the exemplary embodiment, staggereddistribution 300 improves over conventional distribution 100 bydistributing MAP messages 302 at substantially evenly-spaced intervalswithin the same 2 ms window of MAP interval 306.

In exemplary operation, an upstream scheduler (e.g., at the MTS or CMTS,not shown) of the DOCSIS communication system still operates to giveeach service flow of channels 304 only one grant for each MAP interval306, similar to the conventional scheme. However, according to staggereddistribution 300, respective allocation start times of MAP interval 306differ for each upstream channel, but all such allocation start timesnevertheless occur within the boundaries of a single (i.e. the first)MAP interval 306.

For example, as illustrated in FIG. 3 , MAP message 302(1) denotes theallocation start time of MAP interval 306(1) for channel 304(1) (i.e.,CH1), and the respective allocation start times for channels 304(2)(i.e., CH2), 304(3) (i.e., CH3), and 304(4) (i.e., CH4) all occur beforethe expiration of MAP interval 306(1), and before the commencement ofnext MAP interval 306(1)′. In the exemplary embodiment the respectiveallocation start times of channels 304 are distributed substantiallyevenly across the duration of the first MAP interval (e.g., MAP interval306(1)). In this example, for four channels 304 over a 2 ms MAP interval306, the respective allocation start times are staggered according to aformula based on the MAP interval duration divided by the number ofchannels, or 2 ms/4 channels=0.5 ms per channel. More specifically, inthis example, MAP message 302(1) starts at 0 ms, MAP message 302(2)starts at 0.5 ms, MAP message 302(3) starts at 1 ms, and MAP message302(4) starts at 1.5 ms, leaving an equal duration of time (e.g., 0.5ms) between the start of MAP message 302(4) and commencement of next MAPinterval 306(1)′.

Accordingly, in this exemplary embodiment, with four upstream channels304 all using 2 ms MAP intervals, the “effective MAP interval” isactually 0.5 ms (500 μs), which effectively reduces the upstream latencyfor distribution 300 by as much as 1.5 ms. In some cases, it is notedthat, even according to this innovative distribution scheme, particularcomponents of the request-grant loop may not be further reduced (e.g.,MAP generation time and MAP servicing time, described further below withrespect to FIG. 4 ). Nevertheless, in the aggregate, the cumulativeeffect of staggering the allocation start times of the channels 304evenly within a single MAP interval 306 (i.e., by managing the MAPadvance time) enables this dramatic reduction to the effective MAPinterval across the upstream transmission.

FIG. 4 is a sequence diagram illustrating an exemplary transmissionopportunity grant effect 400 according to staggered distribution 300,FIG. 3 . Similar to conventional transmission opportunity grant effect200, FIG. 2 , effect 400 is illustrated with respect to MAP interval306(1) (i.e., the first MAP interval 306), FIG. 3 , which includes afirst component 402 (e.g., representing the 0.6 ms next MAP fulfillabletime), a second component 404 (e.g., representing the 0.2 ms MAPgeneration time), and a third component 406 (e.g., representing the 1.2ms MAP advance time).

In operation of effect 400, a staggered allocation start time for aweight is calculated within a MAC domain 410 (not shown in FIG. 4 ) foreach upstream (US) transmission 412 based on first MAP interval 306(1),according to the formula described above. In the exemplary embodiment,because each of upstream transmissions 412 is a staggered, a fulfillmentwindow 414 for the next MAP interval 306(1)′ is determined onlyaccording to first upstream transmission 412(1). The significance ofthis difference from conventional effect 200 is illustrated in FIG. 4with respect to the depicted comparisons between EXAMPLE 1 and EXAMPLE2.

That is, according to effect 400, a minimum value 416 for therequest-grant loop delay is still the sum of the MAP generation time(i.e., second component 404, e.g., 0.2 ms) plus the MAP advance time(i.e., third component 406, e.g., 1.2 ms), or 1.4 ms. In other words,the minimum unloaded request-grant loop does not change from theconventional technique. However, in contrast to conventional effect 200,according to an exemplary embodiment of effect 400, a maximum value 418for the request-grant loop delay is reduced to the effective MAPinterval, which is the duration (e.g., 2 ms) of MAP interval 306 itself.In other words, maximum value 418 of effect 400 is reduced by 1.4 msfrom maximum value 218 of conventional effect 200, which represents areduction by over 41% to the unloaded request-grant loop delay.

This latency reduction can be seen to further produce dramatic savingswith respect to a granted TxOP 420 as well. As illustrated with respectto EXAMPLE 1, a first TxOP 420(1) (i.e., corresponding to first upstreamtransmission 412(1)) is approximately the same as that granted in effect200, namely, after expiration of the first MAP interval 106, e.g., at 2ms. However, as illustrated with respect to EXAMPLE 2, granted TxOP420(2) (i.e., corresponding to second upstream transmission 412(2))occurs is significantly sooner namely, at approximately 2.5 ms. Asillustrated below with respect to FIG. 5 , as the count of upstreamchannels increases, maximum value 418 approach is the sum of the MAPgeneration time (e.g., second component 404) plus the MAP advance time(e.g., third component 406, or minimum value 416).

FIG. 5 is a timing diagram illustrating an exemplary distribution 500 ofMAP messages 502 for sixteen upstream channels 504 in a communicationsystem implementing DOCSIS. Staggered distribution 500 is similar tostaggered distribution 300, FIG. 3 , except that staggered distribution500 includes four times as many upstream channels 504 over a same singleMAP interval 506 (e.g., 2 ms). Distribution 500 otherwise operatessimilarly to distribution 300, except for the calculation of the staggerduration applied to each successive upstream channel 504. In thisexample, the respective allocation start times are staggered accordingto substantially the same formula (i.e., MAP interval duration dividedby the number of channels), or 2 ms/16 channels=0.125 ms per channel504. Therefore, according to the exemplary embodiment, various MAPmessages 502 may appear to a client device every 125 microseconds.

Accordingly, the present embodiments significantly improve the abilityto unlock the cellular backhaul market, which is traditionally almostentirely reliant on the lower DOCSIS latency. Therefore, the systems andmethods provide a useful new tool for lower DOCSIS 3.0 latency, whichmay, in some instances, be provided with a software update (e.g., to theMTS/CMTS), and thereby enable dramatic latency reductions withoutaltering existing hardware or architectures. In addition to reducinglatency, the present systems and methods further advantageously reducethe jitter experienced by best effort (BE) flows.

The systems and methods described above may be advantageouslyimplemented with respect to conventional DOCSIS communication networkarchitectures. Such network architectures typically include anapplication infrastructure along an upstream communication link to cablenetwork (not shown), and may implement, without limitation, protocolsfor Software Defined Networking (SDN)/Network Functions Virtualization(NFV) Application Development Platform and OpenStack project (SNAPS).Implementation of SNAPS is particularly useful in association with theNFV infrastructure, as well as Virtualization Infrastructure Managers(VIM) that presently utilized DOCSIS and DOCSIS 3.1, which enabledeployment of end-to-end applications.

Additionally, network virtualization provides a software simulation of ahardware platform, and functionality is separated from the hardware torun as a “virtual instance.” Network virtualization further enables thecapability to create, modify, move, and terminate functions across thenetwork in a stable, repeatable, and cost-effective platform. SNAPSadditionally provides transparent application programming interfaces(APIs) for the various infrastructures, and reduces complexity ofintegration testing. The present embodiments are therefore furtherapplicable to an application infrastructure that utilizes a virtualConverged Cable Access Platform (CCAP) core to control a cable plant andmove packets to and from a client device to the customer sites. Thepresent embodiments are of thus particularly advantageous to reducelatency while optimizing the backhaul operation.

The embodiments described above are generally discussed with respect toa conventional cable network, for ease of explanation, but not in alimiting sense. The present systems and methods, for example, are alsoapplicable to optical networks, which may, be formed with an OpticalNetwork Terminal (ONT) or an Optical Line Termination (OLT), and anOptical Network Unit (ONU), and which may utilize optical protocols suchas EPON, RFOG, or GPON. Other embodiments that are contemplated includecommunication systems capable of x-hauling traffic, as well as satelliteoperator communication systems, Wi-Fi networks, MIMO communicationsystems, microwave communication systems, short and long haul coherentoptic systems, etc. X-hauling is defined herein as any one of or acombination of front-hauling, backhauling, and mid-hauling.

In these additional embodiments, above references to the “MTS” may beconsidered as generally interchangeable with the correspondingtermination units of the optical or other networks, such as the ONT, theOLT, a Network Termination Unit, a Satellite Termination Unit, and/orother termination systems collectively referred to as “Modem TerminationSystems (MTS).” Similarly, references to the “modem” may be considered agenerally interchangeable, within the scope of the present embodiments,with such devices or units including a satellite modem, the ONU, a DSLunit, etc., which are collectively referred to as “modems.” Furthermore,although the DOCSIS protocol as described specifically above, theinnovative MAP allocation techniques of the present embodiments are alsoapplicable to other protocols where message allocation can influencelatency, including EPON, RFoG, GPON, Satellite Internet Protocol,without departing from the scope of the embodiments herein.

Accordingly, in an exemplary embodiment, the upstream scheduler may beimplemented in, or associated with, the modem. That is, the modemmanages (e.g., using an upstream scheduling unit or upstream schedulingsoftware module) the upstream traffic according to the low latencytechniques described herein, and sends the managed upstream traffic overa communication link to the MTS. In other embodiments, the upstreamscheduler may be implemented in, or associated with, the MTS. In someembodiments, the communication link between the modem and the MTS is awireless communication pathway (not shown), which may utilize an802.11ad+ communication protocol.

According to the embodiments described herein, a more realistic approachis provided to reduce latency for DOCSIS networks. Such additionallatency reductions are achieved according to the implementation of aninnovative upstream scheduling technique that implements a staggeredallocation approach.

Additionally, although the embodiments herein are described primarilywith respect to upstream traffic, the scheduling techniques may also beadvantageously implemented for some downstream traffic situations. Insuch cases, the scheduling unit (hardware or software-based) may be moreoptimally located within the operational control of the MTS. Althoughupstream traffic often includes different considerations than would thedownstream traffic (e.g., upstream traffic is often considered more“bursty”), downstream traffic nevertheless also experiences latencyproblems, which may be improved according to the present techniques.

Individual modems that support recent DOCSIS versions (e.g., D3.1) canbe field-upgraded to implement the present systems and methods by way ofa software update from the operator. Other modems may be upgraded byhardware modifications. Present systems and methods are advantageouslyapplicable in cooperation with routers provided by either the operatoror the customer. Accordingly, the techniques described herein areoperable to reduce median latency for all traffic, but with no impact toTCP bulk data throughput. The present systems and methods require noadditional configuration from the operator, but may flexibly beconfigured to provide operator control. The low latency DOCSIStechniques of the present embodiments are also applicable to LTE smallcell backhaul in a DOCSIS environment

Exemplary embodiments of systems and methods for low latency upstreamtraffic management and scheduling are described above in detail. Thesystems and methods of this disclosure though, are not limited to onlythe specific embodiments described herein, but rather, the componentsand/or steps of their implementation may be utilized independently andseparately from other components and/or steps described herein.Additionally, the exemplary embodiments can be implemented and utilizedwith respect to downstream traffic, and in connection with othermedication networks utilizing DOCSIS protocols or similarly compatibleprotocols.

This written description uses examples to disclose the embodiments,including the best mode, and also to enable any person skilled in theart to practice the embodiments, including making and using any devicesor systems and performing any incorporated methods. The patentable scopeof the disclosure is defined by the claims, and may include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal language of the claims.

Although specific features of various embodiments of the disclosure maybe shown in some drawings and not in others, this is for convenienceonly. In accordance with the principles of the disclosure, a particularfeature shown in a drawing may be referenced and/or claimed incombination with features of the other drawings.

Some embodiments involve the use of one or more electronic or computingdevices. Such devices typically include a processor or controller, suchas a general purpose central processing unit (CPU), a graphicsprocessing unit (GPU), a microcontroller, a reduced instruction setcomputer (RISC) processor, an application specific integrated circuit(ASIC), a programmable logic circuit (PLC), a field programmable gatearray (FPGA), a DSP device, and/or any other circuit or processorcapable of executing the functions described herein. The processesdescribed herein may be encoded as executable instructions embodied in acomputer readable medium, including, without limitation, a storagedevice and/or a memory device. Such instructions, when executed by aprocessor, cause the processor to perform at least a portion of themethods described herein. The above examples are exemplary only, andthus are not intended to limit in any way the definition and/or meaningof the term “processor.”

Changes may be made in the above methods and systems without departingfrom the scope hereof. It should thus be noted that the matter containedin the above description or shown in the accompanying drawings should beinterpreted as illustrative and not in a limiting sense. The followingclaims are intended to cover all generic and specific features describedherein, as well as all statements of the scope of the present method andsystem, which, as a matter of language, might be said to falltherebetween.

We claim:
 1. A scheduling unit for managing upstream message allocationin a communication network, comprising: a processor configured todetermine (i) a number of channels communicating in one direction streamof the communication network, and (ii) a grant interval duration of thecommunication network; and a media access control (MAC) domainconfigured to (i) calculate a staggered allocation start time for eachseparate channel of the number of channels, and (ii) assign a differentallocation start time, within the grant interval duration, to eachseparate channel, wherein the grant interval duration comprises a firstcomponent indicating a next grant fulfillable time, a second componentindicating a grant generation duration, and a third component indicatinga grant advance duration, wherein the communication network isconfigured according to a request-grant approach for transmissions inone direction stream, wherein the request-grant approach includes afirst request-grant loop latency and a second request-grant loop latencygreater than the first request-grant loop latency, wherein the firstrequest-grant loop latency is based upon a sum of the second componentand the third component, and wherein the second request-grant looplatency is substantially equal to the grant interval duration.
 2. Thescheduling unit of claim 1, wherein the processor is further configuredto grant a transmission opportunity based upon a sum of the secondrequest-grant loop latency and at least one staggered allocation starttime interval.
 3. The scheduling unit of claim 2, wherein the firstrequest-grant loop latency represents a minimum request-grant looplatency value of the communication network.
 4. The scheduling unit ofclaim 2, wherein the second request-grant loop latency represents amaximum request-grant loop latency value of the communication network.5. The scheduling unit of claim 1, wherein the MAC domain is configuredto calculate the staggered allocation start time based on the grantinterval duration divided by the number of channels.
 6. The schedulingunit of claim 1, comprising a modem.
 7. The scheduling unit of claim 6,wherein the modem comprises one or more of a cable modem, a satellitemodem, an optical network unit, and a DSL unit.
 8. The scheduling unitof claim 1, comprising a modem termination system (MTS).
 9. Thescheduling unit of claim 8, wherein the MTS comprises one or more of acable modem termination system, an optical network terminal, an opticalline termination, a network termination unit, and a satellitetermination unit.
 10. The scheduling unit of claim 1, wherein thecommunication network is configured according to at least one of a dataover cable service interface specification (DOCSIS), a 802.11 wirelesscommunication protocol, and a transfer control protocol.
 11. Thescheduling unit of claim 10, wherein the grant interval duration is aMAP interval duration.
 12. The scheduling unit of claim 1, wherein theone direction stream comprises an upstream transmission flow.
 13. Amethod of scheduling upstream data traffic over a communication network,comprising the steps of: determining a downstream grant intervalduration according to a communication protocol of the communicationnetwork; counting a number of upstream transmission channels in thecommunication network; dividing the downstream grant interval durationby the number of upstream transmission channels; calculating anallocation start time interval based on the step of dividing; andassigning each of the number of upstream transmission channels adifferent allocation start time within the downstream grant intervalduration.
 14. The method claim 13, wherein the communication protocol isa data over cable service interface specification (DOCSIS) protocol. 15.The method claim 13, executed by one of a modem and a modem terminationsystem (MTS).
 16. The method claim 13, wherein the downstream grantinterval duration includes a first component indicating a next grantfulfillable time, a second component indicating a grant generationduration, and a third component indicating a grant advance duration. 17.The method claim 16, further comprising granting a first transmissionopportunity at a first allocation start time and a second transmissionopportunity at a second allocation start time different than the firstallocation start time.
 18. The method claim 17, wherein the firstallocation start time is based upon a sum of the second component andthe third component.
 19. The method claim 18, wherein the secondallocation start time is based upon a sum of the first component and thedownstream grant interval duration.
 20. The method of claim 13, whereinthe downstream grant interval duration is a MAP interval duration.